In my opinion, there is a period of time, probably a few days to a week or more, between the onset of flu-like symptoms and actual physician contact. Folks can feel sick or have a cough or a runny nose which is going to result in flu before actually initiating ILI physician contact.

R&D might be able to identify the top search queries that occur a week or two before either CDC or Google Flu Trends data show ILI physician contacts.

Going from detection to prediction would be a useful step to prevent influenza-like illness.